1. Field of the Invention
The present invention relates to a color filter suitable for use in color display devices and a production process thereof, and particularly to a color filter suitable for use in color liquid crystal display devices used in color televisions, car televisions and personal computers, a production process thereof, and a liquid crystal display panel using the color filter.
2. Related Background Art
With the advancement of personal computers, particularly, portable personal computers in recent years, the demand for liquid crystal display devices, particularly, color liquid crystal display devices increases. It is however essential to reduce their cost and moreover to make their performance such as contrast and color reproducibility high for further spreading them.
Color filters used in liquid crystal display devices and the like have heretofore been mainly produced by a pigment dispersing process. In this process, it is necessary to uniformly coat a substrate with a resist, in which a pigment has been dispersed, by spin coating or the like, print a pattern thereon by means of an aligner and further etch unnecessary portions by a wet process. Therefore, this process cannot help going through a highly complicated process. In order to produce a color filter composed of 3 colors, this process must be repeated at least 3 times. Therefore, it takes very lengthy line and process time to produce the filter, which has placed hurdles on the road to reduction in cost.
From the viewpoint of the quality of a color filter, in the case of a color filter according to the general pigment dispersing process, it has been necessary to form the color filter in such a manner that a color filter pattern is laid on top of a light-shielding layer from the point of patterning precision in the process. Therefore, the flatness of the resulting substrate becomes low, which may have formed the cause of defective alignment or the like upon the formation of a liquid crystal cell in some cases.
As a means for solving this problem, there has been proposed a process for producing a color filter by using an ink-jet system. According to this process, an ink-receiving layer formed on the whole surface of a base can be colored on a predetermined pattern composed of a plurality of colors at once, so that great reduction in cost can be attempted. However, color filters are expected to further reduce their cost.
Japanese Patent Application Laid-Open No. 8-313719 has proposed to use a porous layer formed of particles as an ink-receiving layer. However, in this method exposed portions of a light-shielding layer are limited because the light-shielding layer is covered with the ink-receiving layer, so that the light-shielding layer scarcely has the function of preventing color mixing. Therefore, this method fails to produce color filters with a good yield.